The present invention relates to a structure of a semiconductor device for flip chip bonding and a method for producing the semiconductor device.
Most of semiconductor devices have a multi-layer structure in which electrically insulating layers are disposed between the respective layers. Each of the electrically insulating layers has one or more opening portions. There exists wiring for connecting a terminal on a lower side of the electrically insulating layer to a terminal on an upper side of the electrically insulating layer through the opening portion in each insulating layer.
The following method is used for forming such an electrically insulating layer. That is, an opening portion is formed in an electrically insulating layer by the steps of: applying a photosensitive electrically insulating material onto a semiconductor device by a spin coating method; and performing exposure and development thereon. Metal wiring for connecting a terminal on a lower side of the electrically insulating layer to a terminal on an upper side of the electrically insulating layer is formed by the steps of: applying a second photosensitive material onto a layer on the upper side of the electrically insulating layer; performing exposure and development thereon to form a mask; and carrying out a process such as plating, sputtering, CVD, evaporation, etc. The photosensitive electrically insulating material used as a mask is removed after it becomes no longer necessary.
Wiring for connecting a terminal on the lower side of the electrically insulating layer to a terminal on the upper side of the electrically insulating layer can be formed by the aforementioned steps. FIG. 31 is a sectional view showing a part of the semiconductor device formed by the aforementioned steps. In FIG. 31, an aluminum pad 7 is a terminal on a lower side of an electrically insulating layer 12, and a bump pad 3 is a terminal on an upper side of the electrically insulating layer 12. The electrically insulating layer 12 which is formed on a wafer 9 having a semiconductor formed thereon has an opening portion formed over the aluminum pad 7. Metal wiring 11 is formed in an area from the aluminum pad 7 to the bump pad 3 above the electrically insulating layer 12. A bump 10 is formed on the bump pad 3. Incidentally, the formation of wiring in an area from the aluminum pad 7 to the bump pad 3 is termed “redistribution”. In this illustration, the thickness of the electrically insulating layer 12 is selected to be approximately equal to the thickness of the metal wiring 11.
Flip chip bonding may be a model of method of mounting and bonding a semiconductor device, which is produced in the aforementioned steps, onto a circuit substrate such as a printed wiring board. FIG. 32 is a sectional view of a flip chip-bonded semiconductor device. The bump 10 provided on a terminal of the semiconductor device 13 is once melted and then solidified again on the circuit substrate 14 to thereby bond the semiconductor device 13 onto the circuit substrate 14. A gap between the semiconductor device 13 and the circuit substrate 14 is filled with a highly rigid resin. Incidentally, the resin is termed “underfill 15” and effects reinforcement of the junction portion. JP-A-11-111768 discloses an example of flip chip bonding by use of the underfill.